docs: def load(self, module_name):
          """Returns source code and normalized module id of the given module.
  
          Only supports source code files encoded as UTF-8
          """
          module_name, path = self.lookup(module_name)
          if path:
              with open(path, 'rb') as f:
                  return module_name, f.read().decode('utf-8')
          return None, None